Coupling caps

[Leevi]

I have listed here some capacitor types. Which one would you recommend to be used as coupling caps?
Are there any types that should not be used at all?

Polypropylene (e.g. Orange drop, Xicon)
Metalized Polypropylene Tubular (e.g.Illinois capacitor)
Tubular metalized polyester (e.g. Mallory)
Ceramic
Polyester
Polystyrene

/Leevi

[FYL]

No ceramics, except if you want their coloration.

Polystyrenes aren't readily available in high values/high voltage.

All other types are OK.

[Leevi]

Why not ceramics? I think ceramics caps are quite usual in old vintage amps.
/Leevi

[FYL]

Why not ceramics?

Most are highly non linear and distort badly when used in coupling applications.

I think ceramics caps are quite usual in old vintage amps.

Ceramics are fine in vibrato/tremolo circuits. Manufacturers used what was cheap and available, hence small ceramics in tone stacks and other places where plastic or silver mica would have done a much better job.

[HotBluePlates]

FYL already said it.

[Leevi]

If you compare the other types which one do you prefer?
Are there big differences between them? I have used to use Metalized Polypropylene Tubular and have been satisfied with them.
/Leevi

[FYL]

If you compare the other types which one do you prefer?

Er, the ones that fit the board and look nice.

Are there big differences between them?

Yes, in form factor and price.

I have used to use Metalized Polypropylene Tubular and have been satisfied with them.

 

[tubenit]

From ARCHIVES:  previous discussions on coupling caps

http://www.el34world.com/Forum/index.php?topic=478.0

With respect, Tubenit

[jjasilli]

Why not ceramics? I think ceramics caps are quite usual in old vintage amps.
/Leevi

Checkout Angela.com : Old (er, I mean vintage) ceramic caps are cool.  The new ones (allegedly) are not the same. 

[John]

Well shoot! I guess I'll be replacing those 100's next time I order. :)

[simonallaway]

Someone needs to invent "vanity sleeves" for capacitors. You could use good quality modern caps, but have them look like the voodoo/mojo/expensive/noisy/snake-oil caps. Best of both worlds perhaps?

[Leevi]

From ARCHIVES:  previous discussions on coupling caps

http://www.el34world.com/Forum/index.php?topic=478.0

Thanks for the link Tubenit
/Leevi

[Leevi]

Here are some caps numbered from 1 to 8.
If you have extra time please state which type they are.

http://i218.photobucket.com/albums/cc183/kz14100/Caps.jpg

/Leevi

[tommytornado]

Why do you ask?

IMO, Mojotone.com Dijon's (polyester film/foil, a lot like Sozo standards) are the best bang for your buck.   

1-5 are hard to tell..  6 looks to be paper in oil, 7 polystreen, 8 ceramic. 

[bigdaddy]

I tried a ceramic a long time ago and it sounded really good but everyone I had made the volume pot scratchy. But the tone was there, why it would do that I have no idea as far as I know they can't leak.

[Leevi]

Why do you ask?

Because I want to know. Especially I would like to know the type of the number 3.

/Leevi

[FYL]

#3: Evox MMK => metallized polyester

#1 to 5 can be any kind of film caps, European-style (except the yellow tubular). The ones in clear casings could be Rifa X or Y caps. #6 could be a Styroflex. #7 could be a tantalum drop. #8 could be an old-style ceramic.

[HotBluePlates]

FYL did the internet search first, and found the same info. You could find out much of what you wanted to know just by doing a search using the markings on the caps.

The bottom line is that the difference between caps is the dielectris and construction method used, and the different methods used are generally about packing more capacitance in a smaller package. The general rule is that the smaller the cap is for the same capacitance, the more likely it is to deviate from a theoretical perfect capacitor. That means some amount of coloration or non-linearity.

How much is too much? In a guitar amp, that's hard to say. The best and fastest method is to try for yourself in an existing amp, and see what you think of the resulting sound.

[Leevi]

Thanks guys,

#3: Evox MMK => metallized polyester

This is the cap type I have used many times and have nothing to complain about it.

/Leevi

P.S. Sorry, I didn't notice the text "EVOX" on the cap, web search is always useful, I agree

[FYL]

FYL did the internet search first

Just read the markings... Evox + MMK. Evox didn't fully use the European codes for caps, their MMK's are MKT's.

If anyone is interested, here's the DIN Code :

M = Metallized
F = Film

K = Plastic

S, Y = Polystyrene - some MKS are actually FKS caps
P = Polypropylene
C, M = Polycarbonate - Wima MKM caps use a mixed dielectric
T, H, 1 to 9 = Polyester
U, L = Cellulose Acetate

(Edit: added details)

[Leevi]

That helps a lot!
Thanks
/Leevi

[craneclimber]

Polystyrene caps are very heat sensitive, they can change value when soldering.
It would be a good idea to use a heat sink between the iron and the cap.

Don't think I've ever used any, though.

[HotBluePlates]

I've used them. They're always good caps, but only available in small values because of a low dielectric constant. What that means is that they are close to an ideal cap, but are physically large for their capacitance rating. You'll likely only see them in values up to a few-thousand pF or a bit more.

[jjasilli]

Someone needs to invent "vanity sleeves" for capacitors. You could use good quality modern caps, but have them look like the voodoo/mojo/expensive/noisy/snake-oil caps. Best of both worlds perhaps?

      In a sense this is done, especially by old radio restorers, with old cadbaord caps. They aften have wax ends.  The wax is melted and innards removed.  Then new, smaller caps are inserted in the old cardboard tube.  This preserves the old look. 

[craneclimber]

HBP - justradios up in Canada has polystyrene caps ranging from 22 pF to 10000 pF at 630 volts, tolerance is +/- 10%. They claim they are very stable and excellent replacements for ceramic and silver mica in audio circuits.
Prices seem reasonable, most less than $1.00, none higher than $2.00.

[G._Hoffman]

The ones which are kind of getting to me, of late, are the $50-$100 a piece hand made foil in bee's wax caps.  I'm just looking at that and thinking, "Better be careful soldering that thing!" 

You know, when a waiter hands you a wine bottle's cork, you don't actually smell it.  If you do anything with it (it can't actually tell you much), you touch it to your nose to make sure it is still damp (if it is dry, you know the bottle has been stored improperly, which will allow air to get in the bottle and make vinegar).  Mostly, though, you just look at it to make sure it looks normal.  Anything more is just a waste of time.  The term cork sniffing is, therefore, doubly appropriate to me, as it brings in both the arrogance and the lack of real understanding!


Gabriel

[Structo]

Anybody ever try the Roederstein polyester caps?

Mouser carries the Roederstein/ Vishay caps.

I have some on order and will try them on the PI of my D style amp
and a couple other locations.

Right now I have the 6PS series orange drops.

[FYL]

Anybody ever try the Roederstein polyester caps?

Excellent caps. I routinely use them when the board calls for a compact tubular cap

[HotBluePlates]

HBP - justradios up in Canada has polystyrene caps ranging from 22 pF to 10000 pF at 630 volts, tolerance is +/- 10%. They claim they are very stable and excellent replacements for ceramic and silver mica in audio circuits.

Yeah, 10,000 pF (0.01uF) seems to be about the practical limit. That's probably a large cap!

I only used polystyrenes back when I lived in Nashville, cause there was an old-style electronics distributor there that had tons of crap of all descriptions sitting in little bins on many, many shelves. But I don't know I would go out of my way to use polystyrene, unless is was cheaper than the alternative.

[FYL]

Yeah, 10,000 pF (0.01uF) seems to be about the practical limit. That's probably a large cap!

A quite manageable 15 (l) x 13 (dia) mm.

[craneclimber]

You know, when a waiter hands you a wine bottle's cork, you don't actually smell it.  If you do anything with it (it can't actually tell you much), you touch it to your nose to make sure it is still damp (if it is dry, you know the bottle has been stored improperly, which will allow air to get in the bottle and make vinegar).  Mostly, though, you just look at it to make sure it looks normal.  Anything more is just a waste of time.  The term cork sniffing is, therefore, doubly appropriate to me, as it brings in both the arrogance and the lack of real understanding!


Gabriel

Thanks for the primer on proper use/abuse of corks.
My last meaningful encounter with a cork was about 50 years ago. They make great fishing line floats. 

[G._Hoffman]

You know, when a waiter hands you a wine bottle's cork, you don't actually smell it.  If you do anything with it (it can't actually tell you much), you touch it to your nose to make sure it is still damp (if it is dry, you know the bottle has been stored improperly, which will allow air to get in the bottle and make vinegar).  Mostly, though, you just look at it to make sure it looks normal.  Anything more is just a waste of time.  The term cork sniffing is, therefore, doubly appropriate to me, as it brings in both the arrogance and the lack of real understanding!


Gabriel

Thanks for the primer on proper use/abuse of corks.
My last meaningful encounter with a cork was about 50 years ago. They make great fishing line floats. 

Well, I'm not actually a wine connoisseur, but I do play one on dates.  From time to time.


Gabriel

[simonallaway]

      In a sense this is done, especially by old radio restorers, with old cadbaord caps. They aften have wax ends.  The wax is melted and innards removed.  Then new, smaller caps are inserted in the old cardboard tube.  This preserves the old look. 

Is that what I am seeing here? (from another thread about a 6BQ5)  http://hkguns.zenfolio.com/p665440257/h9d9b049#h145ae302

[sluckey]

Is that what I am seeing here?

yes